Materials Science Forum, Vol.457-460, 1321-1324, 2004
Oxidation studies of non-polar 4H-SiC surfaces
The results of a photoemission study of clean and oxidized non-polar (1010) and (1120) surfaces of 4H-SiC crystals are reported. The effects induced in the core levels and valence bands upon initial oxidation were investigated. The surfaces were oxidized gradually from 1 L to 10(6) L while keeping the substrate at a temperature of 800degreesC. Recorded Si 2p spectra show three oxidation states for both surfaces and these are interpreted to originate from Si+1, Si+2 and Si+4, respectively. This is quite different compared to earlier results for the polar surfaces where only Si+4 and one sub-oxide were revealed on each surface. It is concluded that the Si+4 oxide (SiO2) grow as a layer on top of the Si+1 and Si+2 sub-oxides that are located at the interface. The surface/interface related carbon is found to decrease dramatically, but not to be totally eliminated, after the large oxygen exposures made.